Deuteronomy 15:19-20

CAB(i) 19 Every firstborn that shall be born among your cows and your sheep, you shall sanctify the males to the Lord your God; you shall not work with your firstborn calf, and you shall not shear the firstborn of your sheep. 20 You shall eat it before the Lord year by year in the place which the Lord your God shall choose, you and your house.